Pruning By John Mason and staff of ACS Distance Education
Contents Credits 5 Chapter 1 introduction 6 Why, when and what to prune: how pruning affects plants 6 Removing broken branches, dead or diseased wood 7 Controlling the type of growth 9 Controlling the plant s shape and size 10 Promoting healthy, bushy growth 12 Rejuvenating a plant 12 Why prune? 13 Pruning different species 16 Timing for pruning 17 What is compartmentalisation? 18 Chapter 2 types of pruning 19 Cleaning out dead wood 19 Stopping 20 Disbudding 20 Deadheading 21 Pollarding 21 Removing branches 23 Crown cleaning 24 Crown thinning 24 Crown reduction 24 Crown lifting 24 Crown renewal 24 Root pruning 25 Pruning trees in general 26 Pruning larger shrubs 26 Pruning tropical plants 26 Pruning container plants 26 Chapter 3 pruning tools and equipment 28 Secateurs 28 Pruning knife 29 Loppers 30 Pole pruners 31 Hand saws 32
Trimmers 32 Chainsaws 35 Gloves 36 Chapter 4 pruning hedges 37 Selecting hedging plants 39 Establishing a hedge 41 Types of hedge 43 Pruning or trimming an established hedge 44 Rejuvenating old and overgrown hedges 44 Pruning conifers 47 Other hedging techniques 47 Pleaching 47 Tapestry hedges 48 Mazes 48 Chapter 5 shaping plants 49 How to develop an espalier 51 Horizontal espalier 51 Oblique palmette espalier 51 Topiary 52 Portable topiary 55 Other plants suitable for topiary 56 Single-stem topiary 57 Verdant sculptures 58 Bonsai 60 Creating bonsai 61 Pruning bonsai to shape it 61 Chapter 6 managing prunings 63 Composting waste 63 Choosing plants for composting 64 Using compost to improve soils 64 Composting in home gardens 66 Indore method 67 Using lawn clippings 68 Mulching 69 How to lay mulch 69 Biochar 70
Chipping 70 Chapter 7 pruning for fruit production 72 Before buying plants consider the shape 73 Before pruning 73 Points to consider when pruning 74 Pruning specific fruits 75 Citrus spp. 75 Pruning a bush shape 76 Pruning a standard shape 76 Renovating an old citrus tree 77 Open vase shape formative pruning 82 Plum tree pruning 84 Pruning apricots 85 Knowing your buds 86 Chapter 8 pruning roses 95 When to prune roses 96 Pruning techniques for different types of roses 97 Pruning climbers and ramblers at a glance 101 Pruning roses as standards 101 Dead heading roses 103 Rejuvenating an old rose plant 103 Chapter 9 compendium of plants: how to prune what and when 104 Summary: basic pruning guide 104 Glossary 142 Appendix 144 Distance learning and online courses 144 E-books by John Mason and ACS staff include: 145 Printed books by John Mason 146 Useful contacts 147 ACS global partners 147 Social media 147
Credits Copyright 2016 John Mason Written By: By John Mason and staff of ACS Distance Education Photos: John Mason and Stephen Mason Layout & Illustration: Stephen Mason Contributors: Timothy Walker B.A.(Botany), RHS.M. Hort., Post.Grad.Dip.Ed. Adriana Fraser Cert.Hort., Adv.Cert. App.Mgt., Adv.Dip.Hort. Dr Janet Hussein: PhD, MSc, BSc (Hons). Marie Beermann B.Sc. Hort., M.Sc. Hort., Cert. III Ldscp., Dipl. Management, PDC Gavin Cole B.Sc., Cert.Garden Design Published by: ACS Distance Education P.O. Box 2092, Nerang MDC, Queensland, Australia, 4211 admin@acs.edu.au www.acsbookshop.com P O Box 4171, Stourbridge, DY8 2WZ, United Kingdom admin@acsedu.co.uk www.acsebooks.com The information in this book is derived from a broad cross section of resources (research, reference materials and personal experience) from the authors and editorial assistants in the academic department of ACS Distance Education. It is, to the best of our knowledge, composed as an accurate representation of what is accepted and appropriate information about the subject, at the time of publication. The authors fully recognise that knowledge is continually changing, and awareness in all areas of study is constantly evolving. As such, we encourage the reader to recognise that nothing they read should ever be considered to be set in stone. They should always strive to broaden their perspective and deepen their understanding of a subject, and before acting upon any information or advice, should always seek to confirm the currency of that information, and the appropriateness to the situation in which they find themselves. As such, the publisher and author do not accept any liability for actions taken by the reader based upon their reading of this book. ISBN: 978-0-9943737-4-8 page 5
CHAPTER 1 INTRODUCTION Training this peach tree to grow against a wall has many benefits: aesthetic and practical. WHY, WHEN AND WHAT TO PRUNE: HOW PRUNING AFFECTS PLANTS Pruning involves cutting parts off a plant for one, or several, of the following reasons: To remove broken branches, dead or diseased wood which could affect other parts of the plant. To exercise control over the type of growth produced. For example, to promote flowering, fruit or foliage. To control the size of a plant so it doesn t become too large. To control the shape of the plant to improve appearance. To promote healthy and bushy growth. To rejuvenate an old plant by encouraging the replacement of old wood with new wood. If you are not pruning for one of the reasons listed above, then you do not need to prune at all. Many people prune plants just for the sake of it. This is not necessary. Some plants (for example most trees) only need dead or diseased tissue removing (if present) but otherwise can be left. Remember no plant in the wild was ever pruned page 6
and yet they flower and fruit heavily. However in the garden we demand different things from plants than we do from those growing in the wild. In the wild we don t mind if a tree or shrub has become woody or leggy in our gardens we prefer lushness and bushiness and in order to achieve this we prune our garden plants regularly. For many plants, especially garden shrubs, the young growth triggered by regular pruning, not only improves appearance but also increases longevity. The reasons for pruning of plants, as listed above, is achieved in different ways on different plants and is discussed below. Removing Broken Branches, Dead or Diseased Wood Some plants are more susceptible to infection than others when you cut into their living tissue (e.g. birch trees, Betula spp. and some herbaceous plants). Such plants are less able to contain wood rots once they start. Therefore, infected wood should be removed and burnt before the disease spreads. A weeping tree may produce both upright and downward growing shoots. The uprights must be removed and weeping shoots thinned annually if the weeping effect is to be maintained. Platanus orientalis will survive and even thrive with heavy pruning every winter. When a disease attacks plant tissue it typically infects softer growth towards the ends of stems. Plants have adapted to fight the infection by releasing chemicals which form a barrier which the disease can t pass. The tissue on the infected side of the barrier dies off but the rest of the plant is spared. page 7
The dead tissue should be removed because it may provide a base for other pathogens to grow. However, when removing dead tissue it is best not to cut below this barrier otherwise the plant will have to form a new barrier. Clipped balls and hedging brings a sense of order to a garden. Bonsai - R. indicum Kinsai In other cases, it is necessary to cut back into healthy, living tissue. This must be done when the plant has been infected with a fast spreading disease. In these instances, diseases are often visible on the outside of the deadwood. If tissue death has been sudden or rapid do not leave any diseased wood on a plant after pruning. Cut back into living tissue beyond any signs of disease. Make your cuts as neat an as small as possible. This means cutting at right angles to the side of the branch or shoot. The only time to cut on an angle is if the stem or branch is vertical. A right angle cut to a vertical branch will create a surface that is parallel to the ground, water collects more readily and sits on the surface for longer on this type of cut, and this can increase the chance of infection. Use sharp tools which are less likely to tear or bruise plant tissues. Also, only use clean tools. Each time you prune diseased wood you may pick up disease spores on your tools which can then be transferred to healthy wood of the next plant. It is a good idea to dip secateurs in an antiseptic solution when going from one plant to another. No matter what you prune, or for what reason, you should always remove any dead or diseased wood when you spot it. Griselinia can withstand very hard pruning to grow back stronger and healthier than ever. page 8
Removing the growth tips will cause a plant to develop more side shoots and become bushy. Cutting a plant back hard (if it can take it) will cause a flush of lush growth in the next growing season. Long canes of many plants are best managed by tying to a trellis. Controlling the Type of Growth Cutting the roots of a plant, by plunging a spade into the soil or digging a trench, will force a flush of new growth in the roots closer to the base of the plant for many plants. This is particularly true for those with fibrous root systems. This root pruning is used to either prepare a plant for transplanting, or to prevent the roots from spreading into areas where they are not wanted. A problem with this treatment is that it can cause poor health, or death in some plants, particularly if the cuts are made too close to the trunk of the plant. There are three main types of plant growth: roots, vegetative top growth (i.e. leaves and stems) and flower or fruit growth. Discouraging one type of growth can help redirect the energy in the plant towards other types of growth. Removing all flowers and fruit will usually stimulate vegetative growth. Thinning out flowers and fruit will decrease the total number of flowers and fruit, but will usually improve the size and perhaps quality of the remaining fruit. Removing side shoots will generally cause a plant to grow taller more quickly. String between a peg and trowel, used to hold a shoot down encouraging more outward than upward growth. page 9
HOW CLOSE TO CUT TO A BUD These are cut too far away from the bud. The wood between the bud and top of the cut is prone to becoming infected, dying, and then becoming a source of disease that could potentially spread. Controlling the Plant s Shape and Size Any amount of pruning causes some degree of stress to a plant. Ideally, plants of suitable growth and habit should be selected for the site in which they are to be grown but this is not always possible. Also, some people prefer their plants to have a more manicured appearance, perhaps to fit in with a formal garden style. This is potentially cut too close to the bud. When you cut this close; you risk actually cutting and damaging the bud. Fruit trees pruned annually to have growth in the centre removed (allowing better ventilation and light in the middle); and tall shoots are removed, (containing the height and maintaining accessibility) This cut is an appropriate distance above the bud. How to Cut It is important to remember that different plants have different levels of tolerance to hard pruning. With some plants, you can remove 50% of the foliage and this will result in improved vigour and health. With other types of plants, removing 50% of the foliage will cause death. Occasionally you may encounter a plant which has low tolerance to hard pruning that will survive a hard prune, but this is not typical. It is better to find out what are recognised safe pruning limits for a particular plant before pruning it if you are unsure. page 10
Sometimes it is worth taking a risk with an old plant. If you are have shrub that is old and unsightly but you like it that species in that place, then cut it hard back, perhaps even to the base and give it a year to recover. If it regrows you have the plant you want and if it dies then you have a planting opportunity. up to 20%. This means that if more than 20% of the top growth is removed, the Acacia is likely to suffer, or even die. If large branches are growing in a position where you do not want them, it is valid to remove them. If foliage is spreading over a pathway, it is acceptable to cut it back. Similarly, if a branch that bears flowers and fruit is growing where it is not wanted then removal of the branch may be warranted. If a plant is getting too large, then it can be pruned to contain it. This is called cordon pruning - used for decoration or ease of management. One way of expressing a plant s tolerance to cutting back is a as a percentage of the plant s total size. For instance, Acacias may be cut back by If a plant in a garden is growing out of shape, e.g. a hedge or topiary, then pruning to restore the initial shape is recommended. It should be noted that when pruning to control size or shape, frequent light pruning is nearly always better for the plant than irregular heavy pruning. Power tools not only make a big job faster; but can make it easier to achieve an even cut. page 11